Noncorrodible aluminum alloy



Patented June 13, 19331 UNITED, STATES PATENT OFFICE WILLIAM E.MCCULLOUGH, OF. DETROIT, MICHIGAN, ASSIGNOR TO BOHN ALUMINUM & BRASSCORPORATION, OF DETROIT, IVHCHIGAN, A CORPORATION OF MICHIGANNONCOBRODIBLE ALUMINUM ALLOY .No Drawing.

The invention relates to aluminum alloys and has for its object theobtaining of a material having the following characteristics:

First, high resistance to corrosion;

Second, adaptability to formation by extrusion;

Third, capabilityof receiving high polish with the production of anon-tarnishing surface of bright luster.

In the forming of aluminum alloys copper is quite generally used as ahardening agent but as usually manufactured its presence in the alloy isdetrimental to corrosion resistance. I have discovered that by using aboronized copper this tendency to corrosion is very largely overcome. Ihave also discovered that a small percentage of silicon in the alloyimproves its physical characteristics and in the presence of boronizedcopper is not detrimental to either the color, polishing oranti-corrosive properties of the alloy. Ad-

' ditional elements used in the alloy are chromium and cobalt.

One specific example of my improved alloy is of the followingcomposition:

- Percent Aluminum 97.75 Boronized copper .50 Chromium .75 Cobalt .25Silicon .75

My improved alloy is particularly adapted v for exterior finish ofbuildings as it is capable of receiving a highly polished surface andwill retain its bright luster when exposed to weather. The alloy is alsoonly slightly affected by thestandard salt spray test for C corrosionresistance.

Application filed November 2, 1931. Serial No. 572,740.

What I claim as my invention is 1. An aluminum alloy comprising copper.5 to .3%, chromium .75% to 1.5%, cobalt to silicon .75% to 3%, and thebalance of commercial aluminum.

2. An aluminum alloy substantially of the following composition:

Per cent Boronized copper Chromium .75 Cobalt .25 Silicon A .75

In testimony whereof I aflix my signature.

WILLIAM E. MoCULLOUGH.

